How Google creates the description of your website for the result page

How Google creates the description of your website for the result page

Having high rankings on search engines is a great thing. However, it's also important that your web pages are displayed with an attractive description in the search results. If the description is not appealing to web surfers then they might not click the link.
How do Google, Yahoo and MSN/Live create the descriptions and snippets that are used in the search results?
How Google creates descriptions and snippets

Google seems to use the description from the meta description tag if you search for a page by its URL, or if the searched keywords do not appear within the found page.
If the found web page doesn't have a meta description tag then Google seems to use the sentence that contains the searched keyword as the description.
If a web page is listed in the Open Directory Project (DMOZ.org) then Google might also use the description that is used in the DMOZ directory.

How Yahoo creates descriptions and snippets

Yahoo seems to use only the first part of the meta description which is complemented by a text snippet from the searched page that contains the searched keyword.
If a web page doesn't have a meta description, Yahoo will use the description of the web page from Yahoo's directory (if the page is listed there).
If a web page has no meta description and is not listed in the Yahoo directory, then Yahoo will display sentences from the found web page that contain the searched keywords.

How MSN/Live creates descriptions and snippets

MSN/Live seems to use the first sentence that contains the searched keyword as the description. If the searched keyword does not appear on the page, MSN/Live seems to use the first sentence that appears on the page.
If available, MSN/Live will also use the DMOZ directory description in the results.

What does this mean for your web pages?

If you want to make sure that your web pages are listed with an appealing description in the search results, you should use meta descriptions on your web pages. If you don't want to use the description that is used in the Yahoo directory and on DMOZ.org you should use the corresponding tags that prevent search engines from using these descriptions.